1. Priority
Priority is claimed to European Patent Application No. 11 160 515.0, filed Mar. 30, 2011, the disclosure of which is incorporated herein by reference in its entirety.
2. Field of the Invention
The field of the present invention is conveying devices for mixtures of free-flowing finely divided solid materials, in particular for powdered and/or granular (mixed) material, especially polymer granules with a liquid, and particularly a telescopic pipe which is vertically arranged and can be flexibly fitted for conveying a mixture of preferably polymer granules with a liquid, for example, for flushing a contaminated conveying device.
3. Background
The granular product occurring in the reactor during the production of thermoplastics is plasticated in an extruder and formed into individual strands, which are cut into granules by means of a knife rotating in the granulating die. This product may be provided with further components in a further step by compounding.
Compounding is the term used in polymer preparation for producing the finished moulding compound from the raw plastics materials with the addition of fillers, reinforcing agents, plasticizers, coupling agents, lubricants, stabilizers, etc. The compounding is mainly performed in extruders and comprises the process operations of conveying, melting, dispersing, mixing, degassing and building up pressure.
During the granulation, the melt is then forced through the orifices of a die plate, so that subsequently, in the case of strand granulation, initially melt strands are produced, and then during the granulation these strands are turned into cylindrical granules, or else, in the case of die-face granulation, the strands are cut off directly as they emerge at the die plate and are turned into lenticular or spherical granules. The granulation may be performed, for example, in a stream of liquid, which cools the granules and largely avoids agglomeration. The granules are subsequently dried and screened.
Following the granulation after production or after compounding, the product is generally conveyed pneumatically to a silo or bunker. Subsequently, the bulk material is removed from the silos or bunkers and filled into containers or silo vehicles, or the bulk material is put into big bags, such as octabins oder sacks. In each of these steps, dust/coatings may occur, for example due to abrasion, and may in addition to the bulk material itself then cause contamination when there is a change of the bulk material.
Typical bulk materials are, for example, building materials, such as top soil, sand, gravel, ballast or cement, other mineral materials, such as ore or gritting salt, and foods, such as grain, sugar, table salt, coffee or flour, and also powdered materials such as pigments, fillers, granules, pellets, etc.
At the same time, there is an ever increasing need for flexibility, so that in a filling plant devices can be exchanged as and when required. For example, in the case of a bulk material, there may be the requirement for a classifier (dedusting unit), in order to remove fine particles, while for other bulk materials only a conveying pipe is necessary. Moreover, the investment costs are not inconsiderable, and so a flexible solution, for example for using a conveying pipe at different locations of a plant, is made possible.
DE 195 272 40 C1 describes a conveying device, wherein a portion of the conveying line is arranged exchangeably between two abutments spaced rigidly apart and the exchangeable section of conveying line is formed telescopically under the action of a tension spring, and the ends of the telescopic arrangement are supported on the abutments. A disadvantage is the design-related effort correspondingly required for cleaning to avoid contamination as soon as a different solid material is transported, in particular in the pipe-flange region and in the pipe interior.
The requirement for easy exchangeability of buffering and conveying devices before filling or transporting a different type of bulk material is, however, being demanded increasingly frequently.